H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 19)

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• Root Delay—Roundtrip delay to the primary reference source.
• Root Dispersion—The maximum error of the local clock relative to the primary reference source.
• Reference Identifier—Identifier of the particular reference source.
• Reference Timestamp—The local time at which the local clock was last set or corrected.
• Originate Timestamp—The local time at which the request departed from the client for the service
host.
• Receive Timestamp—The local time at which the request arrived at the service host.
• Transmit Timestamp—The local time at which the reply departed from the service host for the client.
• Authenticator—Authentication information.
Operation modes
Devices that run NTP can implement clock synchronization in one of the following modes:
• Client/server mode
• Symmetric peers mode
• Broadcast mode
• Multicast mode
You can select operation modes of NTP as needed. If the IP address of the NTP server or peer is unknown
and many devices in the network need to be synchronized, adopt the broadcast or multicast mode. In the
client/server or symmetric peers mode, a device is synchronized from the specified server or peer, so
clock reliability is enhanced.
Client/server mode
Figure 7 Client/server mode
When operating in client/server mode, a client sends a clock synchronization message to servers with
the Mode field in the message set to 3 (client mode). Upon receiving the message, the servers
automatically operate in server mode and send a reply, with the Mode field in the messages set to 4
(server mode). Upon receiving the replies from the servers, the client performs clock filtering and selection
and synchronizes to the optimal reference source.
In client/server mode, a client can synchronize to a server, but a server cannot synchronize to a client.
Network
Server Client
Clock
synchronization
message
(Mode3)
Automatically works in
client/server mode and
sends a reply
Reply ( Mode 4)
Performs clock filtering and
selection, and synchronizes its
local clock to that of the
optimal reference source